1. Field of the Invention
The present invention relates generally to automotive vehicle suspension systems, and pertains more particularly to an automotive suspension system that is responsive to the inertial forces on the vehicle chassis to counteract and limit vehicle body roll.
2. Discussion of the Related Art
Automotive vehicles have a body or chassis typically with an enclosed operator and passenger compartment with the body being resiliently supported by a suspension system on wheel assemblies that carry it over generally horizontal road and street surfaces. An automotive vehicle may be driven through the rear wheels, the front wheels or both. It typically has steerable front wheels and non-steerable rear wheels. The typical suspension system normally employs springs to support the body on the wheel assemblies, and with damping means in the form of hydraulic cylinders that act to dampen oscillations and movements of the body relative to the wheel assemblies and to reduce the transmission of shock from the wheels to the body.
The construction of the suspension system is often a compromise between a soft suspension for providing a soft comfortable ride for passengers over rough roads and a stiff suspension, which enhances the safety and stability of the vehicle, but is often uncomfortable for passengers. A stiffer suspension transfers more shock of the suspension to the chassis and offers less comfort to passengers but increases the stability of the vehicle. When the typical vehicle enters a turn the resulting centrifugal forces acting on the vehicle tend to roll the vehicle body about its roll center relative to the underlying suspension system. This centrifugal force also tends to displace the body laterally outwardly tending to cause the vehicle to pivot about the contact of its outer wheels with the road surface.
The construction of a vehicle body and the configuration of the vehicle suspension systems determine the location of the roll center. In a conventional vehicle, the roll center of the vehicle is typically below the center of mass or gravity of the vehicle. Centrifugal forces tending to roll the vehicle body act on a lever arm or through a lever arm determined by the vertical distance between the center of gravity and the roll center. This is known as the roll couple.
As a vehicle body moves through a turn the body tends to roll and shift the weight onto the outer wheels and springs while simultaneously unloading the inner suspension springs thereby reducing the cornering traction of the vehicle. The body also tilts or rolls toward the outside of the curve shifting the center of mass of the vehicle toward the outside of the curve. This rolling of the body about its roll center when negotiating a turn is often discomforting to operator and passengers. Stiffer suspensions which tend to reduce this tendency to roll also subjects the passengers and operator to the jolting and jarring of rough roads. A number of approaches to overcoming this tendency of the vehicle to roll during cornering have been proposed in the past. One approach has been to provide the vehicle with anti-sway bars in the form of torsion bars between the two sides of the suspension. While this approach helps reduce roll, it is not satisfactory. Another approach has been to provide the vehicle with linkage system powered by electric motors to selectively tilt the inwardly during cornering. Such a system is disclosed in U.S. Pat. No. 2,152,938. This system is also unsatisfactory for several reasons.
Other attempts at solving the cornering problems have provided for the wheels of the vehicle to tilt into a curve. These have been powered by various means such as electrical and hydraulic systems. One such system that is powered or controlled by the steering of the vehicle is disclosed in U.S. Pat. No. 2,787,473. These systems are generally complicated and expensive.
Others have attempted to overcome this problem by designing the suspension system so that the roll center of the vehicle is disposed above its center of its gravity. Most of these systems are complicated and expensive. These systems also have other serious drawbacks.
I have provided suspension systems in my prior patent applications wherein the suspension comprises an axle assembly for mounting each of a pair of laterally spaced wheels, a spring assembly supporting the chassis on each of the axle assemblies, a moveable arm connected between the spring and the chassis, and an anti-roll linkage connected between the chassis and the moveable arm of the axles of the suspension system being responsive to a lateral force on the chassis, and structured to translate lateral force on the chassis to a vertical force on the down force side of the chassis so that the anti-roll linkage simultaneously lifts the down force side of the vehicle and lowers the up force side of the vehicle. However, I have devised the present system to be less complicated than those.
Accordingly there is a need for an improved simple anti-roll suspension system that overcomes the above problems of the prior art.
The present invention solves the problem of excessive vehicle body roll. Broadly, the present invention provides a suspension system having a linkage that translates lateral body movement into a lift force on the down load side of the body.
More specifically, one embodiment of the invention comprises an anti-roll suspension for a vehicle chassis having at least two laterally spaced wheels, wherein the suspension comprises an axle assembly for rotatably mounting each of a pair of laterally spaced wheels, a spring assembly supporting the chassis on each of the axle assemblies, and anti-roll linkage comprising a pivoting link attached to a lower portion of each side of the chassis, a moveable control arm connected at an outer end to each axle assembly and at an inner end by one of said pivoting links to the chassis xe2x96xa1 and a tie link connected between said pivoting links, said anti-roll linkage structured and configured to translate a lateral force on the chassis to a lateral counter movement of said chassis to the up force side (inside of the turn) of the suspension and a vertical upward movement of the down force side (outside of the turn)of the chassis so that the anti-roll linkage simultaneously shifts the chassis laterally to the up force side of the wheels, lifts the down force side of the chassis and lowers the up force side of the chassis to thereby counteract roll of the chassis.